Calendar1 control isn't visible for SqlDataSource because it nested in formview template. Sou you can't reference to it properties in SqlDataSource parameters.
You can solve the problem by using binding mechanism. The "GTDate" declared in Calendar1 will bind to specified parameter in SqlDataSource.

In .NET 2.0, Microsoft introduced the Web Site. This was the default way to create a web Project in Visual Studio 2005. In Visual Studio 2008, the Web Application has been restored as the default web Project in Visual Studio/.NET 3.x
The Web Si…

Problem
Hi all,
While many today have fast Internet connection, there are many still who do not, or are connecting through devices with a slower connect, so light web pages and fast load times are still popular.
If your ASP.NET page …

The Relationships Diagram is a good way to get an overall view of what a database is keeping track of. It is also where relationships are defined. A relationship specifies how two tables connect to each other.
As you build tables in Microsoft Ac…

Is your organization moving toward a cloud and mobile-first environment? In this transition, your IT department will encounter many challenges, such as navigating how to:
Deploy new applications and services to a growing team
Accommodate employee…